A human heart includes two atrio-ventricular valves through which blood flows from the atria to the ventricles, the valves functioning to prevent return of blood to the atrium. The tricuspid valve, also known as the right atrioventricular valve, is a tri-flap valve located between the right atrium and the right ventricle. The mitral valve, also known as the bicuspid or left atrioventricular valve, is a dual-flap valve located between the left atrium (LA) and the left ventricle (LV), and serves to direct oxygenated blood from the lungs through the left side of the heart and into the aorta for distribution to the body. As with other valves of the heart, the mitral valve is a passive structure in that it does not itself expend any energy and does not perform any active contractile function. The mitral valve includes two moveable leaflets that each open and close in response to differential pressures on either side of the valve. Ideally, the leaflets move apart from each other when the valve is in an open position, and meet or “coapt” when the valve is in a closed position. Problems that may develop with valves include stenosis in which a valve does not open properly, and/or insufficiency or regurgitation in which a valve does not close properly. Stenosis and insufficiency may occur concomitantly in the same valve. The effects of valvular dysfunction vary, with mitral regurgitation or backflow typically having relatively severe physiological consequences to the patient.
Due to the different physical characteristics of the mitral valve as compared to other valves such as the pulmonary valve, percutaneous implantation of a valve in the mitral position has its own unique requirements for valve replacement. There is a continued desire to improve mitral valve replacement devices and procedures to accommodate the structure of the heart, including by providing improved devices and methods for replacing the mitral valve percutaneously.
Replacement of mitral valves is generally performed via surgical technique required open-heart surgery and a cardiopulmonary bypass. Such surgical techniques are not desirable for certain patients. Accordingly, stented prosthetic heart valves have been developed recently to replace damaged heart valves using minimally invasive techniques. Similar transcatheter aortic valve replacement, a stented prosthetic valve for mitral valve replacement includes a prosthetic valve coupled to a stent. The stent is delivered to the site of mitral valve and radially expanded to hold the prosthetic valve in place.
In stented prosthetic aortic valves the stent generally relies of radial forces of the stent to hold the stent and prosthetic valve in place. In some embodiments of stented prosthetic valves for mitral valve replacement, the stent instead uses axial forces for fixation due to the large size of the mitral annulus and the compliance of the left atrium. One exemplary design aims to provide axial fixation by creating tension in the chordae tendinae, thereby holding the inflow section of the stent frame against the mitral annulus. The transition zone between the inflow and outflow sections of the stent frame then provides sealing with the anatomy to prevent paravalvular leakage (PVL) of the transcatheter stented prosthetic mitral valve. FIG. 1 shows a free body diagram showing the forces for such an axial fixation.
However, after delivery and deployment of such a stent prosthetic mitral valve, paravalvular leakage and/or axial motion of the stented prosthetic valve may exist. Currently, there is no treatment for remediation of such axial motion and/or paravalvular leakage after deployment of a stented prosthetic mitral valve. Accordingly, devices and methods are needed for treatment of excessive axial motion and/or paravalvular leakage after implantation of a stented prosthetic mitral valve.